Enhanced nitrogen and carbon removal in natural seawater by electrochemical enrichment in a bioelectrochemical reactor. (1st December 2022)

• Record Type: Journal Article
• Authors: De La Fuente, María José; De la Iglesia, Rodrigo; Farias, Laura; Glasner, Benjamin; Torres-Rojas, Felipe; Muñoz, Diana; Daims, Holger; Lukumbuzya, Michael; Vargas, Ignacio T.
• Is Part Of: Journal of environmental management. Volume 323(2022)
• Publication Date: 2022-12-01
• Subjects: Microbial electrochemical technologies -- Bioelectrochemical reactor -- Nitrification -- Denitrification -- Seawater -- Microbial enrichment; Environmental policy -- Periodicals; Environmental management -- Periodicals; Environment -- Periodicals; Ecology -- Periodicals; 363.705
• DOI: 10.1016/j.jenvman.2022.116294
• Languages: English
• ISSNs: 0301-4797

Abstract

Abstract: Municipal and industrial wastewater discharges in coastal and marine environments are of major concern due to their high carbon and nitrogen loads and the resulted phenomenon of eutrophication. Bioelectrochemical reactors (BERs) for simultaneous nitrogen and carbon removal have gained attention owing to their cost efficiency and versatility, as well as the possibility of electrochemical enrich specific groups. This study presented a scalable two-chamber BERs using graphite granules as electrode material. BERs were inoculated and operated for 37 days using natural seawater with high concentrations of ammonium and acetate. The BERs demonstrated a maximum current density of 0.9 A m −3 and removal rates of 7.5 mg NH4 + -N L −1 d −1 and 99.5 mg L −1 d −1 for total organic carbon (TOC). Removals observed for NH4 + -N and TOC were 96.2% and 68.7%, respectively. The results of nutrient removal (i.e., ammonium, nitrate, nitrite and TOC) and microbial characterization (i.e., next-generation sequencing of the 16S rRNA gene and fluorescence in situ hybridization) showed that BERs operated with a poised cathode at −260 mV (vs. Ag/AgCl) significantly enriched nitrifying microorganisms in the anode and denitrifying microorganisms and planctomycetes in the cathode. Interestingly, the electrochemical enrichment did not increase the total number of microorganisms in the formed biofilms but controlled their composition. Thus, this work shows the first successful attempt to electrochemically enrich marine nitrifying and denitrifying microorganisms and presents a technique to accelerate the start-up process of BERs to remove dissolved inorganic nitrogen and total organic carbon from seawater. Graphical abstract: Image 1 Highlights: Electrochemical enrichment of marine nitrifiers and denitrifiers was accomplished. Enrichment results in removal rates of 7.5 mg NH4 + -N L −1 d −1 and 99.5 mg L −1 d −1 for TOC. BERs showed a max current of 0.9 A m −3 and removals of NH4 + -N (96.2%) and TOC (68.7%). Cathodes were enriched with denitrifies and planctomycetes at −260 mV vs. Ag/AgCl. Electrochemical enrichment emerges as a strategy to accelerate BER start-up.